Topics:

Fetal Ultrasound The Screening Examination

Fetal Ultrasound The Screening Examination

This article also available en Espanol

During the past 15 years I have examined over 40,000 fetuses. Many patients have been referred for Routine Ultrasound Examination, in which the referring physician did not suspect the patient to be at increased risk for problems. When I inquired as to whether the patient or her family had any concerns, the majority confided that their biggest worry was whether their unborn "baby had any problems." The following are questions that a pregnant woman should consider.

How Often Do Birth Defects Occur?

Birth defects occur in 1 in 33 births and may be readily identified at birth because of the external features of the abnormality. Examples may be a spinal cord defect, missing arm or leg, cleft lip or palate, or abnormal facial or head features. However, the majority of serious birth defects are silent--- they involve organs which the pediatrician cannot adequately examine. Examples are:

  • Early hydrocephaly (water on the brain) or other abnormalities of the brain

  • Heart defects

  • Obstruction of the kidneys

  • Blockage of the stomach or intestines

  • Abnormalities of the lungs

     

If I Would Not Terminate A Pregnancy If A Birth Defect Were Identified, What Is The Advantage Of Detecting A Problem Before Birth?

When birth defects are present, but not identified at birth, the child may not become ill until after it is sent home with the parents, only to return with a medical emergency. This is especially important with short maternal stays in the hospital following delivery. It has been demonstrated that the prenatal diagnosis of birth defects may improve the outcome of the child, especially when the birth defects involve the heart or spine.


What Is A Screening Test?

When one considers whether a screening test should be offered to patients, it is important to use a Gold Standard to compare whether the test which is being considered is equal to or superior to screening tests currently in use. Examples of screening tests would be the PAP smear for cervical cancer, mammography for breast cancer, and the Maternal Serum Alpha-Fetoprotein Test to identify fetuses at increased risk for spina bifida or Down syndrome.


Should Ultrasound Be Used As A Screening Test To Detect Birth Defects?

From its early inception, fetal ultrasound has been a useful diagnostic tool when utilized by experts to identify serious birth defects. It has received much attention in the medical literature as well as the public press during the past 15 years. Numerous textbooks, and thousands of medical articles have been written describing its use to identify birth defects. Given its diagnostic potential, physicians in the early 1980's advocated the use of ultrasound to screen for birth defects in women who were low risk; having no family history, or not exposed to drugs or environmental toxins.

While ultrasound appeared to have promise as a screening tool, it later became apparent that its potential benefit was limited by the experience of the physician or technologist performing the examination. Let us explore this in more detail.

On June 20, 1995, Heidi Evans of the Wall Street Journal , wrote an article entitled,


Doctors Who Perform Fetal Sonograms Often Lack Sufficient Training And Skill

In the article, a prominent Professor of Radiology, Roy Filly, at the University of California Medical Center in San Francisco stated,

"Sonography is rife with virtually untrained practitioners who are treating this imaging tool like an open cash register drawer."

The article also stated,

"In 1975, fewer than 5% of doctors did ultrasound in their offices, according to Harvey Klein, president of Klein Biomedical Consultants Inc. in New York. Instead, obstetricians referred patients to hospital radiologists. But when "real-time" scanning came into the picture in the late 1970's, allowing fetal movement to be observed as it happened, the market boomed. Mr. Klein estimates that today, 75% of the country's 39,000 obstetrician-gynecologists have machines and do the tests themselves."

Representative Pat Schroeder, who co-authored the 1992 Mammography Quality Assurance Act, which requires physicians and facilities to meet high standards before mammograms can be performed, stated the following about fetal ultrasound,

"The only thing worse than not having a sonogram is having a bad one."

In addition, the article reported that the poor quality of ultrasound imaging was documented in a study in 1992, by U.S. Healthcare, in which they reported that in 141 second-trimester sonograms-the sonogram that is most crucial for detecting defects in fetal structures-the heart, brain, spine and kidneys were most often poorly or inadequately imaged. In 1994, US Healthcare required obstetricians pass a certification program, of only which 36% passed!

In 1993, the Routine Antenatal Diagnostic Imaging With Ultrasound Study (RADIUS) was published in the American Journal of Obstetrics and Gynecology in which the benefit of routine fetal ultrasound screening of low-risk pregnant women was conducted in hospitals and physicians offices throughout the United States. When compared to obstetricians or radiologists who practiced in a community hospital, the RADIUS study found that there was a significantly higher detection rate of serious birth defects if the ultrasound study was performed by physicians who had extensive training in fetal diagnosis. For example, if the ultrasound was performed by an obstetrician or radiologist at a non-referral center, 0% of serious heart defects were detected!

In another paper analyzing the implications of the RADIUS study, it was reported that if screening ultrasound were performed by experienced physicians, it was the most cost effective method for detecting birth defects. In this study, the author proposed matching the cost of the ultrasound to the experience of the physician. If, for example, the obstetrician rarely detected birth defects, as reflected by the results of the RADIUS study, they should only be paid $50 for the ultrasound examination. If their detection rate was higher, then they should be reimbursed accordingly. This concept would save patients and insurance companies millions of dollars annually.

The most important conclusion from the RADIUS study is that if the ultrasound examination is performed by obstetricians, community-based radiologists, or their technicians, over 85% of major birth defects and virtually all (99%) serious heart defects are missed! This is due to lack of experience of the physician who must divide his or her clinical activities among many different areas, thus precluding the necessary time required to develop expertise in this area of medicine.

What Is The Benefit Of Having A Fetal Ultrasound Specialist Examine My Unborn Baby?

While obstetricians may use ultrasound to determine the fetal heart beat during the first 12 weeks of pregnancy, or examine the amount of amniotic fluid in the last 12 weeks of pregnancy, serious concern has to be raised if they perform an examination of the fetus between 16 and 24 weeks of pregnancy to examine fetal anatomy. Because of the poor performance detecting birth defects as described above, patients should ask themselves whether they should have their screening examination performed by a physician with expertise in examination of fetal anatomy?

The Fetal Ultrasound Examination

Practice Philosophy

It is my philosophy that the ultrasound examination should be thorough, accurate, and a pleasant experience for the patient and her family. The following principles are employed in my practice:

  • Scheduling of patients occurs so that adequate time is allocated for all patients. The difference in time between the patient's appointment and when she is examined averages less 15 minutes 90% of the time.

  • The patient may bring family members or friends to observe the ultrasound examination.

  • Unlike most ultrasound facilities which require a full bladder, I prefer the bladder to be empty. Therefore, the patient is not uncomfortable during the ultrasound evaluation.

  • The patient is not asked to disrobe for the examination. A drape is placed on the patient and the abdominal area is exposed. This maintains patient dignity.

  • Because ultrasound gel is placed on the abdomen of the patient, it is pre-heated so that it will not be cold when applied to the skin.

  • A large screen television monitor is mounted on the wall so that the patient and her family or friends can view the ultrasound examination as it is being performed.

  • If the patient brings a videotape, the examination will be recorded for the patient to keep. In addition, a photo of the fetus will be provided to each patient for their personal use.

  • Dr. DeVore performs and interprets all ultrasound examinations which facilitates increased diagnostic accuracy and better communication of the findings to the patient.

  • Prior to each ultrasound examination, the technique used to examine the fetus is explained to the patient so that she is aware of what will be occurring.

  • Although ultrasound appears to be safe, the examination is conducted for as long as necessary to acquire all of the necessary information to render a diagnosis.

  • If, during the screening examination, evaluation of fetal anatomy is inadequate, the patient is invited to return at a future date to complete the examination. It is our philosophy that neither the patient nor the insurance company is billed if she must return to complete the anatomical survey of the fetus.

  • At the conclusion of the examination a computerized report is generated for the referring physician. If a letter of dictation is required to clarify specific issues, it is dictated in the presence of the patient so that she is aware of what is being stated to her obstetrician. All questions are answered before the patient leaves the office.

Ultrasound Technology

Real-Time Ultrasound

Currently, the most widely used technique for fetal evaluation is real-time ultrasound. This type of ultrasound image is displayed on a monitor and fetal motion can be observed as it occurs. In addition, movement of the heart can be identified. Traditionally, this type of image is displayed in various shades of gray. This is called real-time gray scale ultrasound. However, a newer technique adds color to the image. This is called real-time color ultrasound. The addition of color provides more detail, and as a consequence more information for the physician to evaluate.

Real-Time Plus Color Doppler Ultrasound

The Doppler principle is used in many forms of science, from astronomy, to reporting weather patterns. In fetal ultrasound it is used to detect movement, primarily that of red blood cells. Therefore, the movement of blood within the heart, or other vascular structures, can be identified. The following images illustrate the four-chambers of the fetal heart, with and without the addition of color Doppler. All of the ultrasound evaluations performed by Dr. DeVore use color Doppler to examine the fetal cardiovascular system .

Technique Used To Examine The Fetus For Birth Defects

The technique which I employ to examine fetal anatomy is derived from a similar approach used in computerized tomography in which the body is examined in transverse and longitudinal planes. By approaching the fetal ultrasound examination in a similar fashion, anatomical markers can be examined in a systematic manner. Click on Ultrasound to view a montage of the images, or click on Ultrasound Examination to view individual images of the fetus.

What Is Dr. DeVore' s Detection Rate For Birth Defects?

Detection Rate For Fetuses With Down Syndrome, Trisomy 13, and Trisomy 18

Since 1991, I have conducted an ongoing study. Over 4,000 patients undergoing genetic amniocentesis have been examined with ultrasound using the techniques described above. The results of our study were published this past year in Obstetrics and Gynecology. At the present time over 50 fetuses with Down syndrome (trisomy 21), trisomy 13, or trisomy 18, have been identified following amniocentesis. Of these fetuses, abnormal anatomy was identified with ultrasound prior to the amniocentesis in 98% of fetuses with Down syndrome, trisomy 13, or trisomy 18.

Detection Rate For Congenital Heart Defects

The expected number of children born with severe heart defects is between 2 and 3 per thousand births. In the study reported in Obstetrics and Gynecology, Dr. DeVore's detection rate for severe heart defects was 3/1,000. The following lists some severe heart defects which have been detected during the screening examination of the fetus during the past four years.

  • Hypoplastic Left Ventricle

  • Hypoplastic Right Ventricle

  • Tetralogy of Fallot

  • Atrioventricular Canal Defect

  • Coarctation Of The Aorta

  • Double Outlet Right Ventricle

  • Transposition Of The Great Vessels

  • Truncus Arteriosus

Detection Rate For Major Birth Defects In Low Risk Patients

Dr. DeVore's detection rate for serious birth defects during the second trimester screening ultrasound examination is 10/1,000. This is 5 times higher than the rate reported in the RADIUS study for patients who were examined by their obstetrician or community hospital-based radiologist.

What If My Unborn Baby Has A Birth Defect?

If a birth defect is identified during the ultrasound examination, the findings are discussed with you in detail. Information will be offered to assist your obstetrician in rendering care for you and your unborn child to insure in the best possible outcome.

Can I Be Referred To The Fetal Diagnostic Center For My Ultrasound Examination

Yes!

Salt Lake City Office
Dr. DeVore is available to see patients on Thursday and Fridays at his office in Salt Lake City. He accepts virtually all insurance plans which are currently available in Utah. You can contact his office in Salt Lake City at (801) 359-2229 for further information. While many insurance programs require that you obtain a referral from your doctor, this can simply be obtained by requesting it.

Southern California Offices
Dr. DeVore is available to see patients Monday, Tuesday, and Wednesday at offices in Pasadena (818) 666-3300) or in Tarzana (818) 705-0550, California

Disclosures

 
Loading comments...
Please Wait 20 seconds or click here to close